Hypertension is a major risk factor for the development of early and severe coronary atherosclerosis in countries of western civilization. Treatment of elevated blood pressures has significantly reduced cerebrovascular sequelae of the disease without significant improvement of morbidity and mortality from myocardial infarction resulting from coronary atheroclerosis. These observations led to our experimental study of the potential role hypertension might play in the development of atherosclerosis in a species of subhuman primate, the stumptail macaque (Macaca speciosa). We propose to study the effects of antihypertensive treatment and dietary treatment, alone and combined, in a colony of stumptail macaques in which we have produced renovascular hypertension by a two-stage modified Golblatt procedure and in which an atherogenic diet has been fed. Specifically, three groups of therapy will be studied: 1) drug treatment of hypertension in the presence of a continued atherogenic diet; 2) drug treatment of hypertension with concomitant change to a non-atherogenic diet; and 3) no treatment of hypertension but a change from an atherogenic to a non-atherogenic diet. We will determine whether such treatment will reverse or at least halt acceleration of aortic and coronary atherosclerosis that results from diet and/ or hypertension. Each group will be treated for at least six months. During the course of the experiment, cholesterol levels, blood pressures, and electrocardiograms will be monitored serially. However, the histopathologic observations at the end of the experiment will be the most important aspect of the proposed work. It is hoped that these studies will provide an insight into the relative importance of diet and hypertension in the genesis of coronary atherosclerosis, with the ultimate aim of placing therapy on a more rational and scientific basis.